Won't that damage the engine to have the valve cover off while its running? Also, I checked the dipstick, I've been running the truck since December so it's not time for an oil change yet, but I noticed that the oil on the dipstick is normal color except for at the bottom of the dipstick there is some type of soot mixed in with the oil. I'm thinking maybe burnt oil but not too sure. The oil still has a thick consistency as well. Also, last month, I adjusted the valves because I noticed that some of the pushrods were really loose, but I did it with the motor off and I just manually turned the motor over.